Winter Storm Recap : Nor’easter Thu 11/15 – Fri 11/16

Wow… what a start to the 18-19 winter season!  Our first winter storm system slammed the Hudson Valley Thursday afternoon and evening, and lingered into Friday morning.  The impacts across the region were very significant, causing some parts of the area to be crippled in terms of the Thursday PM commute.  So we’re going to go through this storm in detail, and discuss how our 1st storm of the season caused so much distress on the Hudson Valley.

To begin, lets compare the forecast against what happened.  Below are:
1.  HVW Final Snowfall forecast
2.  The Snow History map… a visual representation of what actually occurred
3.  The Final Snow Reports… from the National Weather Service

The primary criticism that was echoed from the general population across not only the Hudson Valley, but the greater Tri-state area, including NYC… was that nobody was forecasting this much snow, and that “we were completely unprepared”.   There was a widespread feeling about being caught off guard.

So how about our snow totals, where did they stand?  If we break down our forecast into the 3 different forecast ranges [5″-10″, 4″-8″ & 3″-6″], and compare to what actually occurred, how did it compare?  To do this, we try to quantify how much of the area fell within the forecast, and how many areas were outside the forecast range.  Then we will assess the result of our forecast accounting for only the snow totals (not addressing timing or impact).

  • Catskills (zone 1&2): Forecast 5″ to 10″ ….. Western Greene, Delaware & Sullivan County were generally within this range, with lots of 5″ to 8″.  Western Ulster County was on the high end, even exceeding a bit… with West Shokan with 13.0″ and Phoenicia at 11.5″.  Result: Very Good (9/10)
  • Mid & Upper Hudson Valley (zones 3-7): Forecast 4″ to 8″….. Columbia & E. Greene County were within range.  Much of Ulster, Dutchess, & Orange counties over achieved.  Almost every report from those 3 counties fell within a range of 8″ to 12″ instead.  Result: Decent (6/10)
  • Lower Hudson Valley (zones 8&9): Forecast 3″ to 6″…. Westchester, Putnam, and Rockland counties generally saw 5″ to 8″ on average.  There was some overlap, but a lot of 6 and 7 inch totals were common.  Result: Good (7.5/10)

So after looking at the details… the area that saw the greatest difference between the forecast and the result, was the Mid Hudson Valley.  We expected widespread 4 to 8 inches in that area… but saw widespread 8 to 12 inches instead.  A lot has been made of this… probably more than would be made if it was the middle of winter.  Because this was the first storm of the year, and because of the impact on the PM commute, there has been extra frustration around forecasts on this storm.

So why were the totals higher than our forecast?  There were two major reasons, in all actuality… and they’re both related to the same root cause.  Quite simply… it was colder than the computer models projected.  It’s just that simple, and it played out in 2 ways.

  1. Snow ratios were higher than expected.  Snow ratio means how much snow falls, for every inch of liquid precipitation.  The standard average is 10 inches of snow, for every 1 inch of liquid… or a 10 to 1 ratio.  This time of year, because it’s generally milder than mid winter… it’s common to see 8 to 1 ratios… which generates a heavy, wet snow.  But this storm was so cold during the commute… the snow was fluffy and light, which made for 12 to 1, or even 15 to 1 ratios.  So the snow piled up even faster than what we projected in some areas.
  2. More snow fell… and less sleet and freezing rain, than expected.  Also a product of the colder atmosphere.  The total amount of moisture we saw was actually what was projected.  The problem, was the composition of that moisture.  Most locations saw all snow, until the precipitation tapered off between 9pm and midnight (80%+ of storm was snow).  This is different than what the models suggested…

The computer models projected the wintry mix to kick in a little earlier (roughly 65-70% of the storm being snow), which would have kept snow totals a couple inches lower, with a bit more sleet and ice on top of the snow.

Final Forecast Verdict

In total, the forecast was really quite good.  The specific snow amounts may have been 2 to 4 inches higher than forecast in the Mid Hudson Valley… but the impacts we highlighted in the forecast were precisely accurate.  In EVERY text discussion, Facebook Live stream, and radio broadcast discussion we did… we highlighted just how horrible the commute would become.  We spotlighted the trifecta of factors…
1.  First snow of the season
2.  Just in time for PM commute
3.  Intense snowfall rates of 1 to 2 inches per hour

We explained that the very cold conditions would lead to instant accumulations on all surfaces… something that is very abnormal for mid-November.  We explained that the timing could not be worse.  Snowfall rates of 1 to 2 inches per hour, starting between 3pm and 5pm, would lead to conditions being fine one moment… and being extremely treacherous 30 minutes later.  Then factor in that it’s the 1st storm of the season… and it was a recipe for disaster.

If this sounds defensive, it’s not meant to… but it’s meant to be an explainer.  There has been a lot of finger pointing by people in charge, especially in the NYC/NJ area.  The conditions in and around NYC were exceptionally horrible, with major roads at a standstill for hours.  Even locally, reports of 30 minute commutes taking between 2 and 3 hours to travel, had residents furious.  Blame was being placed on local municipalities for not doing an adequate job, for not keeping the roads passable.  That there is no excuse in the northeast for roads becoming parking lots… and people being stranded for hours on the roadways.

The unpopular fact of the matter is… this is what happens when it snows at 1 to 3 inches per hour, for 3 to 4 hours.  Even if road crews had every truck on the road working as efficiently as possible… it is impossible to keep up with those snowfall rates.  This is why we explained repeatedly how truly horrendous the PM commute would be, and to get to your destination before it started.  There were far too many people on the roads, for the type of weather that was occurring.

Hopefully this event will be used as a teaching moment.  Pointing fingers and shirking responsibility won’t help make sure it doesn’t happen again in the future.  We’ll work extra hard to make sure that we get the details as precise as possible, to provide the best information for planning, and keeping people safe.  We’re not always going to get every detail correct, but we can promise you that the difference between 6″ and 10″ was not what caused the problems we saw around the Tri-State.  Thanks for reading… and thanks for all your continued support!

Weekend Roundup : Quiet End to the Weekend

A wild start to the month of November, as we saw a wind blown rain storm push through the Hudson Valley and into the northeast over the last 36 hours.  Here’s the map of preliminary rainfall amounts since Thursday morning, as well as the Poughkeepsie weather almanac for Saturday…

The Hudson Valley is off to a very warm start, over 10 degrees above average for the first few days.  Rainfall amounts are also flooding in across the region.  The average for the month is roughly 3.5 inches of rain… and many areas saw over half of that in the past 36 hours.  With more rain expected in the coming week… we are looking at the likelihood of a wetter than average November.  This continues the 2018 pattern… which saw a brief break in the soaking rainfall during October, where we were actually an inch below average in Poughkeepsie at 3.4″ of rain (average = 4.47″).

So as we look to the end of the weekend… a much more tranquil day on Sunday.  Winds will die down, and sunshine will be the dominant weather story.  Mostly sunny skies with temps in the low 50s should do it.  Making for a fine autumn day.  We’ll have to enjoy that, because some wet weather has its eye on the region for Monday night into Tuesday.  So start factoring that into your plans.  Full details are available on the 5 day forecast.

Thanks for your continued support of HVW!

Summer Rainfall Recap : Super Soaker 2018

Rain… it was the theme of the summer of 2018.  At times, the rain fell lightly… at other times it fell at torrential rates.  But it seems as if it was a day that ended in “Y”, it was raining.  In the 92 days from the start of July through the end of September… 40 of those days had measurable rainfall in Poughkeepsie.  That’s 43.5% of the time that it was raining… so basically every other day it rained in the Hudson Valley.

We’ve had MANY questions about the rainfall this summer, and how it compares to average… as well as if this summer was the wettest ever.  In an attempt to answer this question, we’ve looked at the 3 month period from July 1st through September 30th.  So lets take a look at September first… how much rain fell in the month of September across the Hudson Valley:

September was a very soggy month, but not record breaking by any stretch.  Part of the problem may be that by the time we reached September, we were already rain weary.  With roughly 150% of average rainfall in September, it was surely more than we’re used to… but within reason.  So now, lets look at August and September combined…

Now the water is rising above our ankles.  In an average summer, Poughkeepsie would see roughly 8.5 inches of rain between the months of August and September.  But in 2018, we saw nearly double that… at 14.5 inches of rainfall.  This made sure the grass was always green, and growing like the weed that it is.  The problem being, it was always raining… so when the heck were we supposed to cut the grass?

The Big Picture (July-August-September)

So now, lets look at the entire summer period… from July, through August, and into September.  We’re going to look at 3 graphics:  Total Rainfall, Percent of Average, and Rainfall Amounts Compared to Normal.  Brace yourselves, so you’re not washed away in the monsoon…

Hopefully you’re still with us, and haven’t been washed downstream.  An incredible amount of water fell across the region over the summer.  Roughly 1.5 to 2.0 times the average rainfall on average across the Hudson Valley… and in the Catskills, 2 to 3 times the average rainfall.  Over 20 inches of rain in many areas… and nearly 30 inches of rain in the Catskills!  Truly incredible.

Record Breaking Rainfall?

One of the most frequent questions, has been, “Is this the wettest summer ever?”.  We always say that our ‘weather memory’ is short, and that most times when you feel like “this is the worst its ever been”… when you research the data, you find that may not be the case.  We need to go back only to 2011 to find a comparable 3 month period across the Hudson Valley…

Now… this is not to say 2018 isn’t extreme… quite the contrary.  2011 was an extreme summer across the region, in many cases the worst on record.  In a matter of 2 to 3 weeks, Tropical Storm Irene and Tropical Storm Lee inundated the region with flooding rainfall.  While 2011 saw roughly 1.5 inches more rainfall… 2018 was more consistently wet… with all 3 months seeing 6 or more inches of rainfall.  The rainfall we saw in 2018 was better… because it was spread over a longer period of time, making for less flash flooding incidents than what we saw in 2011.  But any way you slice it… both summers were just amazing in terms of rainfall.

So there you have it… 2018 was not the wettest summer on record, but it certainly was up there.  Make no mistake, the rainfall we saw this year was extreme when compared to average.  We have seen summers this wet in the past… but very, very few can compare to the super saturated summer of 2018.

The Soggy Summer of 2018 – Mid August Analysis

Summer 2018 started out like your typical summer.  May saw slightly below average rainfall, and the month of June was right near normal.  Then an extended heat wave really dried the region out for the first 2 weeks of July… and then everything changed.  We saw a series of upper level low pressure systems get cut off over the northeast.  The result was a persistent SE flow off the Atlantic, and day after day of rainfall… heavy at times.  This has left parts of the northeast under water, with millions of dollars of flood damage.  Hershey Park was left partly under water, a car dealership in NJ saw half its inventory float away, and the issues continue to mount around the region.

So let’s take a look at the rainfall around the Hudson Valley over the last month or two.  We’ll start with the rainfall totals for this past Saturday into Sunday, where we saw a good deal of rain on Saturday with the arrival of the latest upper level low pressure system…

You’ll notice that even on Saturday, parts of the Hudson Valley saw upwards of 2 inches of rain.  Which could have led to some localized flash flooding… but it looks like most areas escaped unscathed in terms of flooding concerns this weekend.  We don’t yet have the stats for Monday’s rain… but surely it will only add to the totals you see above.

But when we step back and take a look at the month of August as a whole, through the 12th… just look at how wet it’s been!

The average monthly rainfall in Poughkeepsie is about 4.2 inches.  So the average rainfall for the first 12 days of the month is roughly 1.6 inches of rain.  What the region has ACTUALLY seen in those first 12 days, is anywhere from 2 to 4 times the average!  Poughkeepsie has seen 5.14 inches of rain so far in August… over 3 times the average so far in August.  Widespread 2 to 6 inch totals have been observed across the Hudson Valley… with some localized areas near the Tappan Zee Bridge nearing 8 inches!  As you head up into the Catskills, you’re looking at a general 4 to 6 inches of rain… mostly due to elevation enhanced rainfall totals.

But if you REALLY want to be in awe… check out the last 30 days of rainfall in the Hudson Valley…

Just a complete deluge of rainfall across a very large area over the last 30 days.  For a region where the average 30 day rainfall is somewhere around 4.4 inches… Poughkeepsie has seen 11.87 inches of rain!  And unlike many summer rainfalls, that is not an isolated amount.  Look at the widespread area of 10 to 15 inches of rain, represented by the bright purple colors.  That’s roughly 3 times the average rainfall over a 30 day period… enough to cause widespread flooding concerns.  Ultimately, it’s been so wet over the past 30 days… that any new rainfall immediately causes flood concerns to rise.  The ground is completely saturated across the region… so we really could use a break from the rainfall.

Sadly, it doesn’t seem to be in the cards.  Projections have additional dips in the jet stream over the eastern US, which will result in multiple chances of rain.

You can see, that the unsettled conditions don’t appear likely to go away any time soon.  We do expect a break for the middle of the week, but multiple fronts are projected to push through the region over the next 10 days… and those could bring additional rain with them.  The concern will be for heavy downpours, where heavy rainfall amounts occur in short periods of time.  That’s where the greatest threat for Flash Flooding will occur.  We’ll have to monitor the situation closely as we move forward.

As wet as this summer has been so far, it’s not unprecedented in the Hudson Valley… not by a long shot.  In 2011, in the matter of 10 days, we saw Tropical Storm Irene and Tropical Storm Lee drop 7.1 and 5.6 inches respectively in Poughkeepsie… for a combined 12.7 inches in just 10 days!  When we look at the 2 month period, we saw a combined 60 day rainfall of 20.73 inches for the month of August and September, which is roughly a FOOT above average!  So while this summer has certainly been soggy… it’s not unheard of.

Hopefully we can get some dry weather to move in over the coming week or two.  But if guidance is detecting the pattern correctly… it looks like there will be more rain in the offing, over the remainder of August.  Thanks for reading!

Severe Weather Report : Tuesday, May 15, 2018

Severe weather comes to the Hudson Valley every year, but thankfully events like what we saw on Tuesday are quite rare.  A significant amount of damage was done, likely millions of dollars of damage when all is said and done across the region.  In addition, lives were lost in this event… and our hearts go out to the friends and family of those who were taken by this storm… our thoughts and prayers are with you.

So we are going to try and recap this massive event.  This severe event was so large in size and scope, that the National Weather Service was not able to account for all of the events in our area.  We have allowed for several days to pass, and for additional reports to come in and verify… but still, there are some cases that are not accounted for on this list from the National Weather Service (NWS).  So please understand that this compiled list and map will not be perfect.  We have utilized the NWS database for the date, and removed reports outside of the Hudson Valley in NY.  So below you will find 3 graphics… one for tornado reports, one for hail reports, and one for wind damage reports.  Below those, is a map with the severe reports plotted by location.

National Weather Service Severe Weather Reports: Tuesday 5/15/18

The storm damage map is likely one of the busiest we’ve ever seen over the Hudson Valley, and it doesn’t even encompass everything that happened.  That said, just look at all of the severe weather reports on this map.  In a ‘typical’ severe weather event for our area, we might see 3 or 4 ‘W’s indicating damaging winds over 50mph… 1 or 2 ‘H’s indicating hail of 1 inch in diameter of more… and maybe a ‘T’ indicating a reported tornado if the outbreak was particularly strong.  This map has too many reports to count.  Above the map, you’ll notice 3 graphics where we’ve

4 Confirmed Tornadoes

The National Weather Service confirmed 4 of the 5 tornadoes that were reported.  The Eldred tornado was classified as a severe downburst, with winds up to 95mph.  But there were 4 confirmed tornadoes, and that is very likely the largest tornado outbreak in recorded history of the Hudson Valley.  There were 2 tornado outbreaks with more confirmed tornadoes in New York… on May 31, 1998 (10) and May 31, 2002 (5).  But those outbreaks were not focused in the Hudson Valley, with the 1998 outbreak being focused upstate (Saratoga area had an EF3), and the 2002 outbreak had 3 tornadoes in the Hudson Valley (1 confirmed in Delaware county, 1 unconfirmed in Dutchess county, and 1 unconfirmed in Putnam county).  Prior to the periods discussed above… tornado data in New York is a bit more difficult to authenticate.  So while we are certain that this was the largest outbreak in the Hudson Valley in at least the last 20 years… and are fairly sure it’s the largest confirmed tornado outbreak in the Hudson Valley’s recorded history… we cannot be 100% sure as of this post, that there was not a larger outbreak at some time.

Countless Reports of Hail and Wind Damage

The map is jaw dropping, with roughly 50 reports of wind damage, and roughly 20 reports of hail in excess of 1 inch of diameter… in addition to the 4 confirmed tornadoes and 1 reported tornado that turned out to be downburst… for a total of 75 severe reports in the Hudson Valley.  In comparison, the May 31, 2002 severe weather outbreak produced roughly 5 reports of wind damage, 9 reports of hail, 1 confirmed tornado and 2 unconfirmed tornadoes… for a total of 17 severe reports in the Hudson Valley.  It would take us a considerable amount of time to look at ALL the data on record to be certain, but it stands to reason that the May 15, 2018 severe outbreak was the largest severe weather event on record for our area.

Cases of Unreported Severe Weather Damage

For all the reports that were submitted to the National Weather Service, there were MANY cases of severe weather damage that were not reported.  Likely the most asked about area, is an area near the Tri-county area where Sullivan, Ulster and Orange counties meet… affectively between Pine Bush, Walker Valley, and Bloomingburg.  The primary road that traverses this areas is Burlingham Road.  We have highlighted this area on the severe weather map above, to demonstrate that there are no severe reports that were given to the National Weather Service.

Due to the high inquiry, with no official reports listed, we (HVW) decided to do a brief assessment of the damage in the region, to see if a tornado had possibly touched down in that area.  After a preliminary review, it’s likely that a strong microburst or macroburst affected that area, with wind gusts over 60 to 80mph likely.  There were dozens… maybe hundreds of trees downed in an area of roughly 10 square miles that we informally surveyed.  Almost all of the debris was facing the same direction… as if a giant knocked over the tree from west to east… meaning that straight line winds were almost certainly responsible.

Hopefully someone from the National Weather Service will take a look at the debris, but this particular area faces 2 problems.  The first, is that it is the intersection of 3 counties… and each county is covered by a different NWS office.  It could easily be difficult to decide which NWS office should send a research team.  The second problem for this area, is that no report was made to the National Weather Service by a trained spotter… and thus the NWS may not be aware of the situation.  We’re not sure if there is a certified NWS spotter in that area, but this is surely one of the problems with reporting and analysis of severe weather events… even today, in 2018.  If the reports don’t get made to the appropriate people, then historically speaking, it’s as if the event never happened.  We’re not sure exactly how to fix this problem… but it’s an issue that is surely worth future discussion.

In Closing…

This was a tremendous event, any way you slice it.  From the severity of damage, to the size of the area damaged, to the number of people impacted, to the duration of time that some areas were without utilities.  We expect that additions and corrections will be made to the data and reports as time goes on… simply because of all the number of things that need to be taken into account.  We welcome additional reports and information in the comments section, and we will try to work those items in where necessary.

We have not had time to go through all the historical data.  In fact, we may not even have access to all the historical data.  Even so, when we compare this event, to one of the most severe outbreaks in the last 20 years… this event (as it pertains to the Hudson Valley specifically) has roughly 4 times as many severe weather reports.  For that reason alone, it stands to reason that this was if not THE biggest event on record in the Hudson Valley, it is surely one of the worst ever.  We hope you made it through safe and sound, with as little impact as possible.  But we know that many of our neighbors were not so lucky.  The community has been tremendous thus far, in responding to those in need.  Lets make sure that we continue to do so.  The Hudson Valley is an amazing place… with amazing people.  Thanks for reading…

Storm Recap : April Snow Fools Nobody

It’s several days after the fact, but we never got to recap our Monday snow event.  So with the weather quiet and cold for this Sunday, let’s instead take a look back at the snow from last week.

Winter continues to plow through the month of March, and straight into April.  When dealing with snow events on or around April 1st… it’s frustrating as a weather forecaster.  Everyone loves a good April Fool’s joke, so everyone wants to assume (or hope) that snow forecasts on April 1st are indeed… just a joke.

Fortunately, or unfortunately… depending on your love or hate for snow and winter… Snow was indeed in the forecast for the night of April 1st and into April 2nd.  It wasn’t a major event in terms of accumulations, but any time you’re dealing with snow in the month of April… it’s a pretty big deal.  So lets take a look at our snowfall forecast, against what actually occurred, and discuss…

A wave of low pressure pushed through the Ohio Valley and eastward to the coast.  As the system reached our area, it ran into cold air, and produced snow over the entire Hudson Valley… with the heaviest amounts focused in the lower half of the valley.

Reports came in of snow and slush covered roads all the way down into the valley areas, which is quite a feat in the month of April.  But when you get a burst of moderate to heavy snow falling in the early morning hours, the road surfaces can cool enough to get accumulation.  Schools across the Hudson Valley had to close yet again in many cases… which will inevitably cost our local kids and educators a nice day in May or June, to make up the lost day.

Many schools tried to hold on to 3 hour delays, because the snow was expected to end between 8 and 10am, and the road conditions would improve rapidly with temps surging into the 40s by noon.  But it’s a REALLY tough call to make, and it’s so easy to sit back and “Monday morning Quarterback” these situations.  When your back is against the wall, and you have to decide whether to send the buses out and begin the day, or close school…. and you look outside and the snow is still pouring down… it’s really hard to stick to your guns and start the school day.

In this particular case we had extremely high confidence in our forecast for the snow to taper in time for delayed schools to open safely.  But we can appreciate why the person making the decision, would err on the side of safety.  Forecasts have been proven wrong before, so even though the forecast says that the snow is going to taper off around 9am… when you see the snow actively falling, it’s tough to put the kids on the bus… banking on the forecast to be right.  Again… it’s always easy to look at the situation after the fact and criticize it.

But it did snow into April… and now the question, is “will it snow again?”.  The jury is out on that… but the possibility is surely there.  Time will tell… but the end of winter is now within view… and warmer weather is on the horizon.  But this was surely an impressive snow event for early April.

Storm Recap 3/13/18: The 3rd Nor’easter’s a Charm

A very active March continues, as we’re only half way through the month… yet we’ve had 3 formidable nor’easters hammer various parts of the northeast.  This time, the Hudson Valley got let off easy, missing out on the heart of this latest storm.  While we saw an accumulating snowfall… by far and away the worst this storm had to offer was focused on New England.

The good news, was that this was expected all the way through.  The data suggested a New England focused storm, our forecast called for a New England centered event… and the storm cooperated and behaved as expected.  Lets look at our forecast map, followed by what actually happened…

Across the Hudson Valley, we expected to see a general 2 to 5 inches, with a few 6 or 7 inch amounts as you got closer to the NY/CT border.  Then as you went into the Catskills and eastern Taconics, we expected to see 5 to 8 inches on the average, with a few locations pushing into double digits.  When all was said and done… that was pretty close to what happened.

The highest totals were certainly the higher elevations of Ulster and Columbia counties, where the upward motion enhanced snowfall amounts just a touch.  Temperatures were pretty much near or just above freezing… making for mainly wet roads across much of the valley locations, but there were certainly some cold spots, where roads became snow covered and travel was rather treacherous.  Driving over a short distance, you could see dramatic changes in the conditions.  For example… I (Bill) travelled from Pine Bush to Middletown, Over that 10 mile trip, I went from…
– just wet roads doing 55mph on rt 302 in Pine Bush, to…
– a snow covered & icy Goshen Turnpike in Circleville, with a car off the road…
– to just wet roads in Middletown again

It was certainly a tricky day of travel, depending on your location.  But like we said, the Hudson Valley was spared the worst of the storm… with a light to moderate snowfall on average, a general 3 to 6 inches.  To experience this storm’s full potential, you needed only hop in your car, and head east 50 to 100 miles… to eastern Connecticut, Massachusetts and Rhode Island…

When we zoom out to look at all of New England, you can see that anyone east of Hartford, CT and Springfield, MA… got absolutely crushed.  The dark orange represents a widespread 12 to 18 inches of snow from Norwich, CT… to Worcester, MA… up to the southern half of Maine.  Then embedded within that large area, are pickets of 18 to 24 inches in red… with up to 30 inches of snow in the dark red areas near Manchester, New Hampshire and Bangor, Maine.  Just some jaw dropping stuff!

It’s been a WILD month of March so far, and indications are that trend will continue into the 2nd half of the month as well.  We can’t thank you enough for trusting HVW to guide you through the storm, and for helping us track the systems with real time reporting that is 2nd to none.  You all continue to make operating HVW a dream come true!  Thanks so much… and hang in there winter warriors… we’ve only got a little further to go.

Major Winter Storm Recap: Wednesday 3/7/18

In the span of just 5 days, the Hudson Valley was punished by 2 major nor’easters. In their wake, these storms have left us with…
– nearly 3 feet of snow in some places…
– thousands of people without power in other places…
– and all of us with a reminder of what winter storms in the Hudson Valley can be like.

So lets take a look at the recap.  We’ll start with the map review of our “Final Snowstorm Forecast” that was issued before the storm began (not the adjusted forecast map that we put out after realizing the storm was going to take a different track).  Next is the “Snow History Map” which shows what actually fell based on a combination of reports and radar data.  Finally will be the National Weather Service Snowfall Totals, which are reported in by NWS trained spotters.

So… before we get out our mental snow shovels and begin to dig into this, in general… if we take the entire Hudson Valley together, we didn’t do too bad.  The southeastern 75% of the Hudson Valley saw 12 to 18 inches of snow on average (or more in some cases).  The northwestern 25% of the region got shorted on snowfall amounts… and we’ll discuss why in a moment.

The Big Winners

So when you look at the map, there is a broken red stripe that runs diagonally from SW to NE across the Hudson Valley.  SE Orange, NW Rockland, bits of Putnam, northern Dutchess and much of Columbia counties… all got crushed by this storm.  Monroe with 27″, Sloatsburg with 26″, Highland Mills with 24″, Hillsdale with 24″, Chatham with 23″, Orange Lake with 20″, Mahopac with 19″… all of those locations, as well as others, were under that little stripe.

The reason those areas hit the snowfall jackpot, has to do with a feature we spoke about numerous times during the forecasting phase of the storm… snowfall banding.  There was a deformation band of snow that set up on the northwest side of this storm… affectively the boundary between the moist flow of air off the ocean, and the cold, dry air on the back side of the system.  This intense band of snow formed over the SE half of the Hudson Valley during mid afternoon, and then slowly pivoted overtop of them.  Resulting in an extended, multi-hour period of snowfall rates at 2 to 3 inches per hour!

Just look at this band of snow… even as of 6:15pm!  When you start to examine where the snow totals were off the scales… it’s no secret as to why areaas like Monroe got 26 inches of snow.  This band hammered them for hours.

The Rip Off Zone

The same image above that highlights the jackpot zone, can tell you exactly where the “rip off zone” is.  The Catskills were spared the heaviest snow totals from this storm.  After initially being projected to see 18″ to 24″ of snow in our final forecast… the storm played a dirty trick on us at the last minute, which we’ll go into momentarily.  But early Wednesday morning, we realized that some big changes needed to be made in our forecast… and by 10am on Wednesday, we released a “now-cast” adjustment to our forecast… and lowered the forecast to 5 to 10 inches across the western HV.

We realized that the storm was going to take a track that would simply rob the western Hudson Valley and Catskills of the moisture we were expecting to inundate those areas.  Sometimes with these dynamic winter storms, it’s not until the storm is just beginning, that you realize a change to the forecast is necessary.  We always talk about “now-casting” during storms, and this is why it’s so vital.  “Now-casting” is the process of using observations, radar data, and actual conditions… to analyze, modify or strengthen your forecast, to provide accurate information to your viewing audience.  As a forecaster, you need to be able to analyze the data in real time, and understand whether an adjustment needs to be made… so that people have the best information possible.

That was what happened in this case.  We received information in real time, that this storm was not developing where it was expected to… and we had to make significant changes on the fly.  Adjusting a forecast from 18 to 24 inches… down to 5 to 10 inches… is a pretty massive change.  When the snow dust settled, the forecast adjustment turned out to be a good one.  Kiamesha & Glen Spey had 12″, Greenville Center 11″, Monticello & Catskill and Phoenicia had 8″… and the area in general was 6 to 12 inches at the end of the storm.

What Happened?…
“Mother Nature is the Boss, that’s what happened.”

So the next part is the fascinating part from a meteorological standpoint.  In short… the guidance was wrong.  It failed to get a good hold on where the center of low pressure was going to develop.  Let’s first take a look at the consensus guidance leading up to the storm…

Guidance had the perfect track for the Hudson Valley, with a rapidly deepening storm hugging the coast until north/central NJ, and then tracking it just south of Long Island, before heading NE toward Cape Cod.  That kind of track will cause a change over to rain in NYC and Long Island, and even into the extreme lower Hudson Valley.  But this kind of track focuses the heaviest band of snow right over the Hudson Valley… pushing a substantial amount of moisture into the HV, and then the storm pivots east, holding the heavy snow in place for many hours.  This track was primed to deposit a widespread 12 to 18 inches of snow in the Hudson Valley, and even more in the Catskills.

However, early on Wednesday morning, we saw indications that the center of low pressure was going to take a significantly different track than what guidance had suggested.  We raced to make changes to our forecast, and when all was said and done, here’s the track that the storm ACTUALLY took

Rather than track up to north/central NJ, near Asbury Park… instead, it stalled it’s northward progression around Atlantic City… before making the turn NE.  This was roughly 50 to 75 miles further south than guidance suggested.  That meant a shift of roughly 50 to 75 miles southeast in the position of heaviest snowfall.  Now, as it turns out… the eastern 2/3 of the HV still got to the forecasted amount… but that was courtesy of the deformation band that stalled out over the eastern HV, providing several hours of 2 to 3 inch per hour snowfall rates.  Anyone who was northwest of that snow band… saw substantially less snow.

The Catskills and western Hudson Valley on average saw 6 to 12 inches of snow.  That’s still a significant snowstorm by almost any standard.  But when you realize that the Catskills would have gotten 18 to 24 inches of snow, if the storm had tracked as guidance suggested… it’s a major change.  If you look at the two maps, the track the storm actually took was drastically different than what was projected just hours before the event.

This is why we always harp on the storm track being so critical.  If the track is further east or west than expected, it’s going to change the end position of the heaviest snow band… and if you live in the area being forecast… it could result in major increases or decreases to your snowfall amount the end of the day.
But it’s also why we can never be ‘certain’ about snowfall totals in a snowfall forecast.  There was no way to see this coming.  There was no data, no guidance that suggested that this storm would track 50 to 75 miles further south and east than expected.  By the time the storm was off the coast of New England, the storm was 100 to 200 miles further east than projected.  These changes happened in real time, as the storm was beginning, and all we can do is make the assessment, and modify the forecast as quickly and effectively… so you have the best information.

From a forecast perspective… we lucked out.  Because the storm still had a strong enough band of heavy snow push into the forecast area of the Hudson Valley.  It provided the 3 to 4 hours of 2 to 3 inches per hour, to get most of the viewing audience close to… or within the forecast range, to where the storm forecast was considered a success.  (Even if we had several people on Facebook yelling about how it was not snowing and the forecast was a bust… despite the fact that we told everyone the snow would not get heavy until the afternoon on Wednesday).  But our viewers in the Catskills certainly would have noticed a difference between the forecasted amounts… and what actually fell.  But hopefully, you at least understand why.

Thank you to everyone who helped us gather data through this storm.  You’re ALWAYS a tremendous help in now-casting any event.  The HVW community provides us with an endless stream of information, that gives us an advantage in forecasting any storm.  You guys are the BEST!  And now… on to the next one, as this recap was delayed because we’re trying to hammer out what will happen with the next nor’easter.  But that’s another conversation…  Thanks for the support!

Winter Storm Recap : One For The Record Books 3/2/18

A very rare, and very damaging storm took aim on the Hudson Valley on Friday.  The impacts were wide ranging, and depending on what part of the Hudson Valley you live in, your experience was dramatically different.  Some of us saw a heavy rain for the majority of the storm, only picking up a slushy coating on the grass late in the afternoon on Friday.  Some of us were on the line between rain and wet snow, and spent the entire day switching back and forth from heavy rain to heavy wet snow… accumulating several inches in the process.  And then there were those of us who saw a heavy wet snow fall from sunrise to sunset on Friday… picking up anywhere from 1 to 3 feet of wet snow, and likely losing power due to trees and power lines snapping under the weight of the wet snow.

We’re going to focus on the meteorological aspects of this storm in this post.  We’re not going to get too far into the damage and power outages.  We have covered those already extensively on Facebook, and you can find a link to one of the discussions right here: Top 5 Most Damaging Storm for Central Hudson.  The damage was incredible, and worthy of it’s own discussion.  If you have time, check out this photo documentary from our good friends at Central Hudson, as they worked to restore power on Saturday.  Some of the pictures are breathtaking.
Central Hudson Storm Restoration Work.

Lastly, a point of clarification… we’re about to talk about this storm from a meteorological standpoint.  We may use descriptions of awe and wonder.  As snow lovers, we may make the storm sound ‘awesome’.  We want to be clear, that in no way are we minimalizing the hardship many people are facing as a result of lost power and damaged property.

So let’s get down to business.  We’ll begin the recap with 3 images:
– Our final snowfall forecast with our mid storm modification
– The snowfall history map
– Snowfall reports via the National Weather Service

Take a good look at that snowfall history map, you likely won’t ever see another one like it.  A literal bulls eye of rain, within a sea of heavy wet snow.  As snow lovers, Alex and I feel punched in the gut by looking at his map.  I live in the SW edge of the ‘snow hole’, and he lives in the NE edge of the ‘snow hole’.  Widespread 6 to 12 inches of wet snow… and nearly nothing at all for many in central Ulster and Northern Orange counties.

Interesting Spotter Reports
The reports out of Ulster are telling… because typically, if you underachieve in an event, or don’t get any snow… a trained spotter simply won’t call the report in.  But 2 people, one in Kerhonkson and one in Saugerties, were so irritated by this storm, that they reported the 0.1″ to the National Weather Service.  If more trained spotters had done that, the ‘snow history map’ would have been more accurate than it was.  To be honest, we believe the map shows too much snow in the ‘snow hole’.  In Pine Bush, I got 0.1″ as well, just a slushy coating on grass.  But it suggests I got 1 to 2 inches.  But aside from splitting hairs, this map paints an incredible picture.

So What Happened??
How on earth does something like this happen?  Is it magic?  Climate Change?  Do the Snow Gods just hate Bill & Alex?  While we believe the answer is actually the 3rd choice… that the snow Gods hate us… there actually is a scientific explanation.  The explanation is quite complex, but let’s walk through it step by step.

Dynamic Cooling: So remember, we were in the 50s on Thursday, and we needed to cool temperatures dramatically just to get to a place where it could snow on Friday.  The mechanism that did this, was called “Dynamic Cooling”.

This was the “vertical velocity” map we posted on Thursday.  It shows the upper level low pressure marked with the “L”.  The bright colors represent intense upward motion, or “lift” in the atmosphere.  The upper level low pressure generated very strong upward motion over the Hudson Valley.  This caused the air to rise very rapidly, which in turn caused the air to cool dramatically.  As the air cooled, it condensed, and rain began to fall heavily.  As the heavy rain fell, it pulled that cooled air back down to the surface.  As this process repeated over time, eventually the column of air was cooled enough so that SNOW was falling instead of rain.  This process is known as ‘dynamic cooling’.  Ultimately, this storm created its own cold air… which is pretty intense meteorological stuff by itself.  But then things got even more complex.

While forecasting, Alex and I began to see the models suggesting it would rain in parts of the Hudson Valley.  With the tremendous dynamic cooling we were expecting, and the heavy precipitation, this didn’t make sense.  Once cold enough to snow, we thought it should continue to snow heavily, at least until the snow eased up later in the day.  This complex riddle resulted in an hour and a half phone call between me and Alex, because we needed to talk about what the heck was going on.  To Alex’s credit… he called it.  He told me over the phone that he thought the model was detecting downsloping winds off the Berkshire Mountains.

What are downsloping winds, and why would it cause rain in the central Hudson Valley?

The winds around a nor’easter originate out of the northeast for the Hudson Valley.  So as the winds rotate around the storm, they blow through Massachusetts, and over the Berkshire Mountains.  As they do that, the air rises and cools over the Berkshires.  This part of the process is called upsloping, and results in higher snowfall amounts and colder temperatures in the Berkshires.

But as the air continues out of the Berkshires, and moves down into the Hudson Valley, the air sinks and drops in elevation.  When air sinks, the opposite happens… the air warms considerably, and dries out.  The result is quite amazing.  Temperatures were falling due to the dynamic cooling process.  At our HVW Station in Hurley, NY… check out these temperatures, and see if you can notice when the downslope effects started to be felt:
12am: 38.3°… 1am: 36.3°… 2am: 34.8°…(skip a few hours)…  6am: 34.7°… 7am: 37.8°… 8am: 38.4°… 9am: 38.1°

So the dynamic cooling had begun to take effect, and it was resulting in a change over to sleet and wet snow… but once the downsloping effect kicked in, it negated the effect of the dynamic cooling, and made it too warm to snow over a portion of the viewing area.

The map above is a bit of a crude demonstration of the location of the Berkshire Mountains, factoring in the northeast wind, and the net impact area.  Now, you might wonder why the ‘rip off’ zone or ‘snow hole’ is many miles away from the Berkshires.  The reason, is because the elevation remains rather high with the Taconics, and elevation doesn’t decrease with the Hudson Valley until you get much closer to the river.  So the downsloping effect doesn’t really kick in until you get closer to the river.

From a forecasting perspective it’s frustrating… because like I mentioned, Alex called it in our conversation.  And we then discussed it repeatedly, in both posts and live streams, as a possible wildcard.  But we hesitated to nail down a specific area, because it was not something we had seen before… at least not to this magnitude.  But now, having experienced it, we know that it can happen.  Pretty wild stuff.

Blockbuster Wet Snow

So now that we’ve highlighted the meteorological phenomenon that caused a large area in the middle of the region to get do little snow, let’s show the snow map once more, and soak in those incredible snowfall totals…

AMAZING snow totals.  Ignoring the previously discussed snow hole, and we had widespread 6 to 12 inch amounts across the  Hudson Valley.  As you went up in elevation across Dutchess and Columbia counties, you even broke 12 inches.  Unfortunately, we also saw wind gusts reports in the 30 and 40mph ranges.  When we forecasted 6 to 12 inches of wet snow, along with those wind gusts… we were concerned that power outages would become a widespread problem.  We hope that power gets restored ASAP, as it’s really tough this time of year to not have power.

Then there’s the Catskills… woo doggy… the Catskills.  Just take look at Greene county.  28 inches for Hunter, 26 inches for Windham, and similar high numbers of 1 to 3 feet across the Catskills.

This storm was truly dynamic, and when you stack it up against other historical storms… you see just how unique and significant it was.